Techniques for performing the automated closing of tubular knitted articles, particularly hosiery items, at an axial end thereof, at the end of their production cycle on circular hosiery knitting machines, are known.
Some of these techniques are based on picking up the article, at the end of its production cycle, from the circular hosiery knitting machine and on transferring it to a sewing or looping station, which is generally arranged laterally with respect to the machine used to produce the article.
In the sewing or looping station a sewing or looping head is provided, by means of which the axial end of the article, usually constituted by the axial end at which the production of the article has ended, is closed.
Some techniques are based on the use of a single device both to pick up the article from the machine that produced it and to support the article during the sewing or looping operation to close its axial end. In other techniques, a device for picking up the article and transferring it to the sewing or looping station and a handling device which is arranged in the sewing station and is used to prepare the article for the subsequent sewing or looping operation and optionally to move the article during sewing or looping with respect to the sewing or looping head, are provided.
Usually, the article is picked up from the machine that produced it and optionally transferred to the handling device by engaging individually the loops of knitting of the last formed row of knitting of the article, and the loops of knitting of a half-row of said last row of knitting are made to face individually the loops of knitting of the other half-row before proceeding with sewing or looping, so that the axial end of the article is closed by joining in each instance two mutually facing loops of the two half-rows that compose the last formed row of knitting. Thanks to this fact, an excellent result is achieved in terms of precision and aesthetics in the automated closing of axial ends of tubular knitted articles, particularly hosiery.
In both of these techniques, quite often the sewing or looping operation is performed on the article turned inside out, so that the sewing or looping chain stitch is scarcely visible on the right side of the article, i.e., on the side that normally is visible when the item is being worn.
For this reason, in sewing or looping stations designed to perform these techniques for closing an axial end of tubular knitted articles generally there is a turner, which is designed to turn inside out the article, which is picked up in the right-side-out configuration from the machine that produced it, before subjecting it to the sewing or looping operation and optionally to turn it again in order to bring it to the right-side-out configuration after the sewing or looping operation.
One of the most widespread types of turners for this type of use is based on the use of a tubular body that is made to face in a downward region the article that is supported by means of a pick-up device or by means of a handling device at its axial end to be closed and is arranged substantially vertically with said axial end directed upwardly. The tubular body also is arranged so that its axis is vertical, so that its upper axial end faces the hanging article. The interior of the tubular body is then connected to suction means so as to aspirate, through its upper axial end, the article, which remains in any case retained, at its axial end to be closed, by the pick-up device or by the handling device. The tubular body is then raised so as to pass, with its upper axial end, through the axial end of the article that is engaged with the pick-up device or with the handling device. As a consequence of this passage, the article is everted on the outer lateral surface of the tubular body and is extracted progressively from the upper axial end of the tubular body, turning it inside out.
In the case of significantly long tubular articles, such as for example in the case of pantyhoses, difficulties can be encountered in obtaining, with turners of this kind, the complete eversion of the article onto the outer lateral surface of the tubular body. Similar problems are encountered when the article must be returned to the right-side-out configuration, by means of a new turning, after performing sewing or looping. This new turning is in fact performed by sucking the article into the tubular body through the lower axial end of the tubular body. In this case also, a considerable length of the article can in fact hinder its complete suction through the lower axial end of the tubular body of the turner.
In order to solve this problem, turners have been devised which have very long tubular bodies and therefore have substantial vertical space occupations, which make locating and installing these turners difficult. As an alternative, turners have been devised which are provided with rollers that have horizontal axes and face the outer lateral surface of the tubular body. These rollers can be actuated on command with a rotary motion about the respective axes and can move toward the outer lateral surface of the tubular body, so as to engage the portion of the article that is already everted onto the outer lateral surface of the tubular body, so as to complete its eversion, or away from the outer lateral surface of the tubular body so as to not interfere with it in other operating conditions.
The use of rollers to assist and complete the eversion of the article on the outer lateral surface of the tubular body, while allowing to reduce the vertical space occupation of turners, is not devoid of drawbacks.
The action of the rollers can in fact be scarcely tolerated by particularly delicate articles, which may break due to the friction produced by the rollers.
Moreover, the rotary action of the rollers on the article can be scarcely productive in terms of the entrainment of the article on the outer lateral surface of the tubular body in the case of very glossy articles.